The present invention relates to generators, in more detail to those generators which are light, small, inexpensive, efficient in power generation, and suitable especially as bicycle generators.
Generators of this kind have generally been designed to generate electromotive force by allowing a coil to rotate in a magnetic field of a permanent magnet.
According to the conventional technology, generators for bicycles, etc. have employed a permanent-magnet rotor which is placed inside a stator, or a stator with coils wound on each of four slots of a core which is placed inside a permanent-magnet rotor ring. These structures, incapable of increasing the number of coil windings, have required, for supply of sufficient electromotive force, permanent magnets made of expensive materials such as aluminum-nickel-cobalt alloy. A limitation has also been experienced on the performance with these structures.